﻿//////////////////////////////////////////////////////////////////
//
// SafeAsyncInvoker.cs
//
// Copyright (c) 2012 Dan Pike.
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation files
// (the "Software"), to deal in the Software without restriction,
// including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software,
// and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;

namespace Utilities
{
   public static class SafeAsyncInvoker
   {
      ////////////////////////////////////////////////////////////////////////
      //
      static SafeAsyncInvoker()
      {
         pending_ = new List<KeyValuePair<IAsyncResult, Control>>();
      }

      ////////////////////////////////////////////////////////////////////////
      //
      public static bool Flush()
      {
         try
         {
            // Clean up any completed Async operations
            lock (pending_)
            {
               pending_.RemoveAll(KVP =>
               {
                  IAsyncResult checkResult = KVP.Key;
                  Control checkHost = KVP.Value;
                  if (checkResult.IsCompleted)
                  {
                     if (!checkHost.IsDisposed)
                     {
                        checkHost.EndInvoke(checkResult);
                     }
                     // This AsynResult is complete, remove it from our list
                     return true;
                  }
                  // Still waiting for this asyncResult to complete
                  return false;
               });
            }
            return true;
         }
         catch (System.Exception)
         {
            // Cannot output exception, we may be inside the logger!
         }
         return false;
      }

      ////////////////////////////////////////////////////////////////////////
      //
      public static bool BeginInvoke(Control host, MethodInvoker method)
      {
         try
         {
            IAsyncResult result = host.BeginInvoke(method);
            if (!result.CompletedSynchronously)
            {
               // Remember the IAsyncResult so that we can clean it up later
               lock (pending_)
               {
                  pending_.Add(new KeyValuePair<IAsyncResult, Control>(result, host));
               }
            }
            Flush();
            return true;
         }
         catch (System.Exception)
         {
            // Cannot output exception, we may be inside the logger!
         }
         return false;
      }

      ////////////////////////////////////////////////////////////////////////
      //
      private static List<KeyValuePair<IAsyncResult, Control>> pending_;
   }
}
